Direct interlocking device for the breech block and the firing pin of automatic firearms



Sept. 5, 1933. scorn 'E AL 1,925,776

\ DIRECT INTERLOCKING DEvIcE FOR THE BREEGH BLOCK,

, AND THE EIRING EIN 0F AUTOMATIC FIRBARIS Filed Feb. 24.. 1932 III/Illll AZ redod'collz' Invert 0155.

Giovanni aZizlsid/izze/oilz' Patented Sept. 5, 1933" 1,925,176 DIRECT INTERLOCK-ING DEVICE FOR THE BREECH BLOCK AND THE FIRING AUTQMATIC FIREARMS PIN OF Alfredo Scotti, Giovanni Battista Anelotti, and Bortolo Giuseppe Campi, Brescia, Italy Application February 24, 1932, Serial No. 594,884,

and in Italy February 24, 1931 Claims.

The invention has for its object an arrangement applicable to automatic firearms in which are provided means adapted to prevent the firing pin from detonating the cartridge before the' Firearms are already known in which there, are provided parts adapted-to retain the firing,

pin until the moment when the breech block has reached the position where thebreech is completely closed and in many cases these parts are controlled by the breech block, which moves forwardly and rearwardly and rotates at the ends of the reciprocating movements in co-operation with other parts arranged in the 'breech of the firearm.

Firearms are also known in which there are provided locking members controlled by the suc--' cessive movements of the barrel, by a gas piston or by similar means which hold the breech block in the ,,closed position until the gas pressure resulting from the explosion is sufficiently reduced.

In all these known arrangements additional members are necessary; these members must have as small bulk as possible and are conse- 5 quently of light construction, although they are subjected to continuous and powerful hammer after reaching the position where the. breech is closed, ceases to restrain the firing pin which,- in its turn, advances and positively efl'ectsthe V which the firing pin '4 is adapted to slide and with 105 locking of the breech block in the closed 'position and retains it in this position until a-certain member, which is displaced by the release of the explosion gases orotherwise, returns the said firing pin into the disengaged position.

very undesirable According to the present invention these time; 7

trigger spring usually employed for the actua- .tion of the firing pin; the said breech block;

breech block is provided in known manner with projections which engage in grooves formed in the breech, a small forward end portion of which has a helicoidal form so as to cause rotation of at least part of the breech block about the axis of the firearm; thisarrangement is characterized in that the firing pin, which is positively urged by the restoring spring, is provided with shoulders which press against a flange arranged inthe breech and that the said flange is provided with indentations which arrive opposite the shoulders of the firing pin when the breech block effects its final closing rotation, so as to permit of the shoulders entering therein to complete the stroke of the firing pin and to effect the tangential locking of the breech block which cannot again move rearwardly until the firing pin is returned again by a suitable part of the gun actuated by the release of the explosion gases.

x The subsequent retraction of the firing pin which. is necessary in order to disengage its shoulders from the indentations of the breech block to permit the latter to rotate as it recedes in its turn, may be effected by the recoil of the gun or by a gas piston 'or known type; for this 0 purpose it is suflicient to provide the firing pin with a projection formed and arranged so as to be capable of actuation by the member selected for this purpose.

In order to render more clear the essential na- 35 tune a d scope of the invention, one constructional example is illustrated in the accompanying drawing, in which: Figs. 1 and 2 are two side views of an automatic firearm. which illustrate the same in two positions, namely with the breech open and closed respectively:

3'is a longitudinal section of Fig, 1.

Figs. 4, 4a,,4b show respectively a. side view, a front view-and a cross section of the firing pin provided with the shoulders and the engaging Figs.-' 5, 5a and 5b are similar illustrations or the breech block.

1 ln theqconstructional example. illustrated, the

breech block 5 recoils under the action of the explosion gases and is'retumed to the closed positionby a restoring spring 6. The said breech lock is provided with a longitudinal cavity, in

projections 51: which engage in grooves 5b formed in the breech of the firearm, said ,grooves 5b having at, their foremost end helicoidal deviations 50. When the breech block returns tothe closed position, it is guided y t projecti tion by means of the helicoidal deviations 5c of said grooves. This known arrangement is made use of to assure the operation of the arrangement according to the present invention.

The firing pin in this firearm isnotprovided with a special trigger spring but it is actuated positively by the restoring spring 6. The firing pin has two shoulders 4a, 4b which normally abut against the edge of a flange formed in the breech: in the example shown this flange consists merely of the circular edge of the rear surface of the breech block. The shoulders 4a, 4b transmit to the breech block the pressure of the restoring spring which returns it to the closed position. During this forward movement the firing pin occupies a somewhat backward position in the breech blockwhich does not permit [it to reach the cartridge. But the edge of the retaining fiange .in the breech block is provided with indentations 5d, 5e which, owing to the final rotation of the breech block arrive opposite the shoulders 4a, 4b; under the action of the spring 6 the firing pin can then advance a little further in the breech block, which is in its closed position, and; consequently reaches the point where it detonates the cartridge.

The engagement which is thus efiected between the shoulders 4a, 4b of the firing pin and the indentations 5d, 5e of the breech block prevent the latter from rotating so as to be able to recoil, so that the firing pin effectively locks the breech block in its closed position during the first period of the release of the explosion gases. This engagement always takes place very smoothly and perfectly balanced since it takes place in a tangential direction and not in an axial direction as is the case in known arrangements.

In the constructional example illustrated, the unlocking of the breech block is entrusted to an ordinary gas piston 3, working in a cylinder 2 arranged at a convenient part of the barrel 1 of the firearm. This piston, before the bullet leaves the barrel, is forced rearwardly by the gases which enter the cylinder 2 and retracts the projection 40 which is integral with the firing pin. The firing pin is then moved rearwardly and frees the breech block which, under the action of the remaining gas pressure, recoils in turn after having executed a partial rotation in the helicoidal grooves 50, which movementbrings the unindented portion of the flange of the breech block opposite the shoulders 4a, 4b of the firing pin; under theaction of the gases the breech block completes its .recoil stroke carrying with it the firing pin and loading the restoring spring 6. Naturally the projection 4c of the firing pin could be actuated by the recoil of the barrel if the arrangement is applied to a firearm with a recoil ing barrel. I

In the constructional form shown the projection 40' of the firing pin is made use of to retain the firearm in the cocked position and ready to be discharged, since this projection can be engaged with the projection 4d of the tumbler. This engagement keeps the return spring 6 strained and the breech block cannot complete itsfor ward stroke until the tumbler is displaced.

This arrangement adds the further advantage to an absolute minimum, they are of simple'design and easy to manufacture and they are not liable to any kind of derangement..

Naturally the constructional arrangement of the diiferent parts will have to be varied in accordance with the type and the nature of the automatic firearm to which the invention is applied, but such alterations will be obvious to persons skilled in the construction of firearms.

What we claim is:

1. In an automatic firearm comprising a barrel, a breech in said barrel, a breech block adapted to close said breech, a firing pin adapted to detonate cartridges inserted in said breech, said breech having grooves formed therein and projections on the breech block adapted to slide in said grooves, said grooves being formed at their ends with helicoidal deviations adapted by cooperation with said projections to cause a partial rotation of said breech block, the provision on said firing pin of shoulders and in said breech block of indentations, said breech block being rotatable with respect to said firing pin, said shoulders being adapted, upon effective closure of said breech, to enter said indentations thereby permitting the said firing pin to detonate a cartridge in said breech.

' 2. In an automatic fire arm comprising a barrel, a breech in said barrel, a breech block adapted to close said breech, a firing pin adapted to detonate cartridges inserted in said breech, said breech having grooves formed therein and projections on the breech block adapted to slide in said grooves, said grooves being formed at their ends with helicoidal deviations adapted by cooperation with said projections to cause a partial rotation of said breech block, theprovision on said firing pin of shoulders and in said breech block of indentations, said breech block being rotatable with respect to said firing pin, said shoulders being adapted, upon effective closure of said breech, to enter said indentations thereby permitting the said firing pin to detonate a cartridge in said breech, and means actuated by the force of the explosion gases for unlocking said breech.

3. In an automatic firearm comprising a barrel, a breech insaid barrel, a breech block adapted to close said breech, a firing pin adapted to detonate cartridgesin said breech, said breech having grooves formed therein and projections on the breech block adapted to slide in said grooves, said grooves being formed at their ends with helicoidal deviations adapted by cooperation with said projections to cause a partial rotation of said breech block, the provision on said firing dentations, 'said shoulders being adapted, upon effective closure of said breech, to enter said indentations thereby permitting the said firing pin to detonate a cartridge in said breech, and-means actuated by the force. of the explosion gases and including a piston and a gas cylinder for unlocking the breechof said firearm.

4. In an automatic firearm comprising a barrel, a breech .in said barrel, a breech block adapted to close said breech, a firing pin adapted to detonate cartridges inserted in said breech, said breech having grooves formed therein and projections on the breech block adapted to slide in said grooves, said grooves being formed at their ends with helicoidal deviations adapted by CO? operation with said projections to cause a partial rotation of said breech block, theprovision -on said firing pin of shoulders and in said ing adapted, upon effective closure of said said grooves-said grooves being formed at their ends with helicoidal deviations adapted by cooperation with said projections to cause a partial rotation of said breech block, the provision on said firing pin of shoulders and in said breech block of indentations, said shoulders being adapted, upon effective closure of said breech, to enter said indentations thereby permitting the said firing pin to'detonate a cartridge in said breech,

a projection for withdrawing the firing pin and thereby unlocking the breech of said firearm, a

tumbler, a projection on the tumbler and a return spring constantly urging said firing pin forwardly, the said projection on the tumbler being adapted to keep the return spring of the arm strained and consequently to retain-the firearm in the cocked position in such a way that the barrel contains a cartridge only at the moment of firing. v

ALFREDO SCO'I'TI. GIOVANNI BA I'I'ISTA ANELOTII. BORTOLO GIUSEPPE CAMPI. 

